Arrhenotoky, also known as arrhenotokous parthenogenesis, is a form of parthenogenesis in which unfertilized eggs develop into males. The set of processes included under the term arrhenotoky depends on the author.[1] Arrhenotoky may be restricted to the production of males that are haploid, or include diploid males that permanently inactivate one set of chromosomes (parahaploidy) or be used to cover all cases of males being produced by parthenogenesis (e.g. aphids where the males are XO diploids).[1] However, when both males and females develop from unfertilized eggs, the term "deuterotoky" is usually used instead.[2]

Arrhenotoky occurs in members of the insect order Hymenoptera (bees, ants, and wasps),[3] and the Thysanoptera ('thrips').[4] The system also occurs sporadically in some spider mites, Hemiptera, Coleoptera (bark beetles), and rotifers.

In the most commonly used sense of the term, arrhenotoky is used synonymously with haploid arrhenotoky : the production of haploid males from unfertilized eggs in insects having a haplodiploid sex-determination system. Males are produced parthenogenetically, while diploid females are usually[nb 1] produced biparentally from fertilized eggs. In a similar phenomenon, parthenogenetic diploid eggs develop into males by converting one set of their chromosomes to heterochromatin and inactivating them.[6] This is referred to as diploid arrhenotoky.[7]

See also


  1. ^ unless in certain rare cases they too are produced by thelytokous parthenogenesis[5]


  1. ^ a b Normark, B. B. (2003). "The evolution of alternative genetic systems in insects". Annual Review of Entomology 48: 397–423.  
  2. ^ Gavrilov, I.A.; Kuznetsova, V.G. (2007). "On some terms used in the cytogenetics and reproductive biology of scale insects (Homoptera: Coccinea)" (PDF). Comparative Cytogenetics 1 (2): 169–174.  
  3. ^ Grimaldi, David A.; Michael S. Engel (2005-05-16). Evolution of the Insects. Cambridge University Press. p. 408.  
  4. ^ White, Michael J.D. (1984). "Chromosomal mechanisms in animal reproduction". Bolletino di zoologia (free full text) 51 (1-2): 1–23.  
  5. ^ Pearcy, M.; Aron, S.; Doums, C.; Keller, L. (2004). "Conditional Use of Sex and Parthenogenesis for Worker and Queen Production in Ants". Science 306 (5702): 1780–1783.  
  6. ^ Nur, U. (1972). "Diploid arrhenotoky and automictic thelytoky in soft scale insects (Lecaniidae: Coccoidea: Homoptera)". Chromosoma 39 (4): 381–401.  
  7. ^ Nur, U. (1971). "Parthenogenesis in Coccids (Homoptera)". Integrative and Comparative Biology 11 (2): 301–308.